Special Colloquium
Department of Physics, NCU
Magnetotransport in carbon and topological nanomaterials due to novel charge trajectories
Speaker
Dr. Ching-Hao Chang (張景皓)
IFW Dresden (Germany), 德國萊布尼茲固態物理與材料研究所
Date 2018.01.2 (Tue)
Time 14:00
Place S4-625
Abstract: When a charge carrier moves at a plane that is subject to a perpendicular homogeneous magnetic field, it curves into a closed cyclotron orbit, which finally leads to the well-known Hall effect. Nowadays, the advanced nanotechnology is continually gifting us with nanoarchitectures that have not only rich forms of geometry, but also novel topology in electronic states. In this talk, I will introduce new classes of magnetic states induced by the geometry and the topology.
We recently found that the snake orbit [1] appears in curved carbon nanomaterials. In a carbon nanotube, we demonstrate that the snake orbit results in a large non-saturating magnetoresistance measured in experiments [2]. In a rolled-up graphene, we predict that the formation of snake orbit leads to a strongly direction-dependent positive magnetoresistance with an anisotropy up to 80% [2,3]. Moreover, exotic magnetotransport properties recently observed in topological nanomaterials are also related to novel magnetic states, which are introduced by the interplay between the electronic-state topology and the nanostructure geometry [4-6].